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Prostate CancerPhase 1/2REPAIRNCT04536805

Relapse in Previously Irradiated Prostate Bed : Stereotactic Ablative Reirradiation Potentiated by Metformin

A Phase 1/2 study testing Metformin, Stereotactic Body Radiation Therapy (SBRT) 30 Gray (Gy) and Stereotactic Body Radiation Therapy (SBRT) 36 Gy in people with Prostate Cancer, run by Institut Cancerologie de l'Ouest at 12 sites in France.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

This phase I/II escalation dose study is assessing the efficacy of the recommended dose of stereotactic re-irradiation (SBRT) of relapses within the prostatectomy bed, potentiated by metformin Read more about this study

Who is it for?
Ages 18 years and older, men only
Conditions the study is for
Prostate Cancer
What is being tested?
Metformin, Stereotactic Body Radiation Therapy (SBRT) 30 Gray (Gy) and Stereotactic Body Radiation Therapy (SBRT) 36 Gy
Type of treatment
Surgery or procedure
Could I receive a placebo?
No, everyone receives an active treatment
How many people
44 participants
Where
12 sitesFrance
Study dates
17 Nov 2020to Nov 2031
Phase
Phase 1/2
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • Men only
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Written informed consent according to International Conference on Harmonisation (ICH)/ Good Clinical Practice (GCP) regulations before registration and prior to any trial specific procedures.
  • Biochemical recurrence occurring at least 2 years after external radiotherapy to the prostate lodge and the end of hormone therapy, for prostatic adenocarcinoma previously treated by radical prostatectomy.
  • Local recurrence in irradiated areas proven by biological (PSA > 0.2 ng/ml and ascending confirmed by at least 2 successive assays) and radiological (lesion visible on MRI and/or Choline PET and/or Prostate-Specific Membrane Antigen (PSMA) PET).
  • Recurrence without rectal invasion
  • Pelvic and prostate MRI evaluation
  • Absence of pelvic lymph node or metastatic recurrence proven by choline PET or PSMA PET scan
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  • World Health Organisation (WHO) performance status 0-1
  • Low risk, intermediate risk and high risk with a single risk factor
  • PSA doubling time > 6 months
  • No anti-cancer treatments planned for the current relapse, including hormone therapy.
  • Age > 18 years old.
  • Life expectancy greater than or equal to 5 years.
  • Patient registered with a health insurance system.
  • Patients willing and able to comply with the planned visits, treatment plan, laboratory tests and other study procedures indicated in the protocol.

Who cannot join

  • Metastatic disease (bone, lymph node or other)
  • Late radiotherapy urinary or gastrointestinal toxicity (grade ≥ 2) (after radiotherapy of prostate lodge)
  • History of cancer in the 5 years prior to trial entry other than cutaneous basal cell carcinoma
  • Inflammatory bowel disease
  • Contraindications for performing MRI
  • Rectal surgery history
Show all 23Show fewer
  • Patient treated for Diabetes
  • Creatinine clearance < 45 mL/min
  • Treatment with metformin in the last 3 months prior to inclusion
  • Severe comorbidity that may affect treatment, for example :
  • Acute bacterial or fungal infection requiring intravenous antibiotics at the time of inclusion.
  • Unstable angina, myocardial infarction and/or congestive heart failure requiring hospitalization within the last 6 months
  • Myocardial infarction in the last 6 months.
  • Exacerbation of Chronic Obstructive Pulmonary Disease (COPD) or other respiratory conditions requiring hospitalization or preventing metformin therapy at the time of inclusion.
  • Any condition associated with an increased risk of lactic acidosis (e.g., alcohol abuse, New York Heart Association (NYHA) III or IV congestive heart failure).
  • Clinically significant history of hepatopathy with Child-Pugh B or C score, including viral infection or hepatitis, alcohol abuse or cirrhosis.
  • Any acute or chronic condition that may result in tissue hypoxia (e.g. heart or respiratory failure, shock).
  • Bilateral hip prosthesis
  • Treatment with any investigational drug or participation in a clinical trial within 30 days prior to inclusion.
  • Known hypersensitivity to metformin or any of its components
  • Inability or reluctance to swallow oral medications
  • Persons deprived of liberty, under a measure of safeguard of justice, under guardianship or under the tutor authority
  • Inability to undergo medical monitoring of the trial for geographical, social or psychological reasons.

Trial locations and contacts

12 sites in 1 country.

12 sites in 1 country

France12 sites

  • Institut de Cancerologie de L'Ouest

    Angers, 49055

  • CHRU de BREST - HOPITAL MORVAN

    Brest, 29200

  • Societe de Recherche Oncologique Clinique 37 (Roc 37)

    Chambray-lès-Tours, 37170

  • Centre GEORGES FRANCOIS LECLERC

    Dijon, 21079

  • Clinique Victor Hugo

    Le Mans, 72100

  • Centre OSCAR LAMBRET

    Lille, 59020

  • Centre LEON BERARD

    Lyon, 69373

  • Centre Eugene Marquis

    Rennes, 35042

  • Centre Henri Becquerel

    Rouen, 76038

  • Institut de Cancerologie de L'Ouest

    Saint-Herblain, 44805

  • ICANS - Institut de cancérologie Strasbourg Europe

    Strasbourg, 67200

  • Chru Bretonneau

    Tours, 37044

Other trials in France

About this study

Official title: Relapse in Previously Irradiated Prostate Bed : a Phase I/II Study of Stereotactic Ablative Reirradiation Potentiated by Metformin

This phase I/II escalation dose study is assessing the efficacy of the recommended dose of stereotactic re-irradiation (SBRT) of relapses within the prostatectomy bed, potentiated by metformin

Read the detailed description

The purpose of this escalation study is, first to select the recommended dose of re-irradiation SBRT in combination with Metformin (based on treatment toxicity monitoring) and then to estimate the efficacy of re-irradiation SBRT in combination with Metformin.

Five or six fractions, at a level of 5 or 6 Gray (Gy) per session (either 5 x 6 Gy, 6 x 6 Gy, or 5 x 5 Gy), will be delivered over a maximum of 12 days (from day 1 to day 10 or 12) to provide a total dose of 25 to 36 Gy.

Patient receive oral Metformin treatment from Day -15 and Day 75.

Patient will be followed for 5 years: patients visits will be planned at week 2; 4; 8; 12; and month M6; M9; M12; M18; M24; M36; 4 years and 5 years.

Conditions
Prostate Cancer
Being tested
Metformin, Stereotactic Body Radiation Therapy (SBRT) 30 Gray (Gy), Stereotactic Body Radiation Therapy (SBRT) 36 Gy, Stereotactic Body Radiation Therapy (SBRT) 25 Gy
Keywords
Prostate Cancer, Stereotactic Body Radiation Therapy, SBRT, Metformin, Previously Irradiated Prostate Bed, Biochemical recurrence
Medical subject headings
Prostatic Neoplasms

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • MetforminDrug

    Metformin: 850 mg per day (day -15 to day 0) 1700 mg per day (day 1 to day 75)

  • Stereotactic Body Radiation Therapy (SBRT) 30 Gray (Gy)Radiation

    Also called SBRT

    Stereotactic Body Radiation Therapy (SBRT): Dose escalation 5 x 6 Gy day 0 to day 10

  • Stereotactic Body Radiation Therapy (SBRT) 36 GyRadiation

    Also called SBRT

    Stereotactic Body Radiation Therapy (SBRT): Dose escalation 6 x 6 Gy day 0 to day 12

  • Stereotactic Body Radiation Therapy (SBRT) 25 GyRadiation

    Stereotactic Body Radiation Therapy (SBRT): Dose escalation 5x 5 Gy day 0 to day 10

Study groups in NCT04536805
Study groupRoleWhat they receive
Metformin + SBRT at total dose of 30 Gray (Gy)ExperimentalMetformin: 850 mg per day (day -15 to day 0) 1700 mg per day (day 1 to day 75) Stereotactic Body Radiation Therapy (SBRT): Dose escalation 5 x 6 Gy, (day 0 to day 10)
Receives: Drug: Metformin; Radiation: Stereotactic Body Radiation Therapy (SBRT) 30 Gray (Gy)
Metformin + SBRT at total dose of 36 GyExperimentalMetformin: 850 mg per day (day -15 to day 0) 1700 mg per day (day 1 to day 75) Stereotactic Body Radiation Therapy (SBRT): Dose escalation 6 x 6 Gy (day 0 to day 12)
Receives: Drug: Metformin; Radiation: Stereotactic Body Radiation Therapy (SBRT) 36 Gy
Metformin + SBRT at total dose of 25 GyExperimentalMetformin: 850 mg per day (day -15 to day 0) 1700 mg per day (day 1 to day 75) Stereotactic Body Radiation Therapy (SBRT): Dose escalation 5 x 5 Gy (day 0 to day 10)
Receives: Drug: Metformin; Radiation: Stereotactic Body Radiation Therapy (SBRT) 25 Gy

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. For phase 1:. Select the recommended dose for SBRT (either 5 x 6 Gy, 6 x 6 Gy, or 5 x 5 Gy), in combination with Metformin

    SBRT toxicity will be reported during the 12 weeks following the initiation of SBRT.

    Measured: 12 weeks

  2. For phase 2: estimate the efficacy of re-irradiation SBRT in combination with Metformin in terms of biochemical relapse-free survival rate.

    PSA levels will be assessed every 3 months within 3 years after SBRT.

    Measured: 3 years

Secondary outcomes (7)

  1. Estimate the efficacy of re-irradiation SBRT in combination with Metformin in terms of biochemical relapse-free survival and biochemical response

    PSA levels will be assessed every 3 months within 5 years after SBRT.

    For all patients, visits will be made at 6, 9, 12, 18, 24, 36 months, 4 years, and 5 years will be made from the start of SBRT. The end of the trial is defined by the last visit of the last included patient.

    Measured: 5 years

  2. Estimation of the efficacy of SBRT re-irradiation in combination with Metformin in terms of progression-free survival and overall survival

    Clinical progression-free survival is defined as the time interval between the date of SBRT start and the date of clinical progression (local progression assessed by the physical examination, or appearance of metastatic lesions), start of hormonal therapy or death irrespective of the cause.

    Measured: 5 years

  3. Evaluation of acute and late genitourinary and gastrointestinal toxicities of the SBRT re-irradiation

    Acute and late genitourinary toxicities over the first 5 years will be assessed according to the NCI-CTCAE V5.0 classification

    Measured: 5 years

  4. Evaluation of Quality of life after SBRT re-irradiation in combination with Metformin

    Quality of life will be assessed based on EORTC Quality of life questionnaire (QLQ)-C30 scale at week 4; 8; 12; and month M6; M9; M12; M18; M24; M36; 4 years and 5 years. The Time Until Definitive Deterioration (TUDD) will be computed from registration until the first observation of a definitive deterioration of the quality of life, defined as a score decreased by 10 points (in the case of global health scale and functional scales) or increased by 10 points (in the case of symptom scales) compared to the score at baseline, without later improvement superior to 10 points compared to baseline score.

    Measured: 5 years

  5. Evaluation of Quality of life after SBRT re-irradiation in combination with Metformin

    Quality of life will be assessed based on EORTC Quality of life questionnaire in prostate cancer (QLQ-PR25) scale at week 4; 8; 12; and month M6; M9; M12; M18; M24; M36; 4 years and 5 years. The Time Until Definitive Deterioration (TUDD) will be computed from registration until the first observation of a definitive deterioration of the quality of life, defined as a score decreased by 10 points (in the case of global health scale and functional scales) or increased by 10 points (in the case of symptom scales) compared to the score at baseline, without later improvement superior to 10 points compared to baseline score.

    Measured: 5 years

  6. Evaluation of urinary symptoms

    Urinary symptoms over the first 5 years will be assessed by International Prostatic Symptom Score (IPSS). This score evaluates the severity of prostate symptoms in the last month on a scale of 0 to 35 (total of 7 items rated 0 to 5).The distributions of this score will be described at inclusion, at follow-up visits (M6 M9 M12 M18 M24 M36 4 and 5 years) and at the end of the study visit according to the following categories:

    0 - 7: Poorly symptomatic ; 8 - 19: Moderately symptomatic ; 20 - 35: Severe symptoms.

    Measured: 5 years

  7. Evaluation of erectile function

    Erectile function will be assessed by International Index of Erectile Function (IIEF5). This score assesses erectile function over the past 6 months on a scale of 1 to 25 (total of 5 items rated 0/1 to 5). The distributions of this score will be described at baseline, at follow-up visits (M6 M12 M18, M24,M36 4 and 5 years old) and at the end of the study visit according to the following categories:

    1 - 4: Non-interpretable ; 5 - 10: Severe erectile dysfunction ; 11 - 15: Moderate erectile dysfunction ; 16 - 20: Mild erectile dysfunction ; 21 - 25: Normal erectile function.

    Measured: 5 years

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted3 Sep 2020
  2. Study start17 Nov 2020
  3. Primary completionNov 2031 (estimated)
  4. Study completionNov 2031 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1/2
Primary purpose
Treatment
Allocation
Non-randomised
Intervention model
Sequential
Masking
None (open label)
Enrolment
44 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT04536805
Sponsor's protocol ID
ICO-2020-01
Acronym
REPAIR
Status last verified
Jun 2026
First submitted
17 Aug 2020
Last updated
23 Jun 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Yes: Individual participant data that underlie the results reported in the primary study manuscript after deidentification (text, tables, figures and appendices)

Publications

  • Joly A, Blanc Lapierre A, Rio E, Vaugier L, Supiot S, Guimas V. REPAIR_GETUG P16 relapse in previously irradiated prostate bed: a phase I/II study of stereotactic ablative reirradiation potentiated by a metformine study protocol. BMJ Open. 2025 Jul 24;15(7):e100031. doi: 10.1136/bmjopen-2025-100031.

    PubMed 40707156

Questions about this trial

What is this clinical trial studying?

A Phase 1/2 study testing Metformin, Stereotactic Body Radiation Therapy (SBRT) 30 Gray (Gy) and Stereotactic Body Radiation Therapy (SBRT) 36 Gy in people with Prostate Cancer, run by Institut Cancerologie de l'Ouest at 12 sites in France.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 14 inclusion and 23 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: under way, not looking for participants, as of the sponsor's last update on 23 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 12 sites in France. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this combined phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

For phase 1:. Select the recommended dose for SBRT (either 5 x 6 Gy, 6 x 6 Gy, or 5 x 5 Gy), in combination with Metformin (time frame: 12 weeks). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT04536805, which also lists 1 linked publication.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 23 Jun 2026.

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